Slovenian Matej Mohoric gave Bahrain Victorious something to cheer with his second stage win in this year's Tour de France two days after French police searched his team's accommodation and vehicles amid an investigation into potential doping.

Mohoric, who had already prevailed in the seventh stage in Le Creusot, attacked from the breakaway to wrap up a solo victory on the 19th stage, a 207-km ride from Mourenx, virtually zipping his mouth shut as he crossed the line.

The French prosecutor's office in Marseille on Thursday said it had opened a preliminary investigation into the Bahrain Victorious team after police searched the outfit's hotel.

It said the investigation was into "acquisition, transport, possession, import of a prohibited substance or prohibited method for use by an athlete without medical justification."

Bahrain Victorious said they were complying with the investigation.